BULLETIN OF THE GEOLOGICAL SOCIETY OF AMERICA 

 Vol. 7, pp. 363-376, PL. 17 MaRCH 14, 1896 



GEOGRAPHIC RELATIONS OF THE GRANITES AND PORPHY- 

 RIES IN THE EASTERN PART OF THE OZARKS 



BY CHARLES ROLLIN KEYES 



(^Presented before the Society December 26 , 1895) 



CONTENTS 



Page 

 Introduction 363 



General geological features of the region 364 



The crystalline rocks 365 



Types represented 365 



Lithological characters of the granites 366 



Lithology of the porphyries 367 



Consanguinity of the acid rocks 368 



Origin of the massive crystallines and their present configuration 369 



Summary of opinion 369 



Recent investigations 369 



General areal distribution.' 370 



Physiography of the region 370 



Main characteristics 370 



Tertiary peneplain 372 



Farmington lowland plain 373 



Relations of principal types of acid rocks to physiographic provinces 374 



Age of the massive crystallines 375 



Summary 376 



Introductory. 



The granitic rocks of Missouri are the only massive crystallines occur- 

 ring between central Arkansas and lake Superior and between the Appa- 

 lachians and the Rocky mountains. They are the most ancient rocks 

 exposed in the central Mississippi basin. As irregular, discontinuous 

 fields and isolated hills the crystalline masses are scattered over a district 



XLII-BuLL. Geol. Soc. Am., Vol. 7, 1895. (363) 



